Trimming mechanism



Sept. 24, 1957 s. G. BRADY TRIMMING MECHANISM 2 Sheets-Sheet 1 Filed June 25, 1956 INVENTOR.

SAMUEL G. BRA DY ATTORNEYS Sept. 24, 1957 s. G. BRADY 2,807,255

TRIMMING MECHANISM Filed June 25, 1956 2 Sheets-Sheet 2 2 Q2 Al Bl L R R I v Tm Q" LL Q- r r M4 3 I I M K M M' M3 FIG.2.

v INVENTOR.

ATTORNEYS interference.

United States Patent P 2,807,255 TRINIMING NIECHANISM Samuel G. Brady, Birmingham, Mich., assignor to The Gear Grinding Machine Company, Detroit, Mich., a corporation of Delaware Application June 25, 1956, Serial No. 593,395 3 Claims. (Cl. 125--11) The invention relates to trimming mechanism for form grinder wheels and is of the general construction forming the subject matter of my pending application, Serial No. 538,053, filed October 3, 1955. In common with this case the instant invention is for a construction in which different portions of a continuous contour are simultaneously trimmed by cutters of separate trimming mechanisms, each of which is movable to a common point in said contour and may even overlap a portion trimmed .by the other. It is obvious that if these cutters reach the same point at the same time there would be However, such result is avoided by an operating mechanism through which when one cutter is at said common point or on the overlapping portion of the trimmed contour, the other will be in a position sufficiently spaced therefrom to avoid interference. In my former application the separate trimming mechanisms were each actuated by a hydraulic cylinder piston motor, the hydraulic fluid passing from one cylinder to the other and holding the pistons in predetermined relation to each other. Such motors are never completely leak proof, so that in time this relationship might be altered bringing about interference between the two mechanisms. It is therefore the primary object of the instant invention to obtain a construction in which the separate trimming mechanism are at all times positively held in non-interferring relation to each other. To this end the invention consists in the construction as hereinafter set forth.

In the accompanying drawings:

Fig. l is a front elevation of a trimming mechanism assembly with the cover of the housing removed.

Fig. 2 is a vertical section on line 2-2 of Fig. 1.

Fig. 3 is a horizontal section on line 33 of Fig. 1.

As shown in Fig. 1 the housing A is wide at the base and tapers to a narrower portion at its upper end. It comprises a backing plate A on which the mechanisms are mounted and a hood or cover A for enclosing the same with the exception of the upper end where the trimming cutters are located. B and C are pantographs for the separate trimming mechanisms which, as shown, have generally vertically extending members B, B C, C and laterally extending members B B C C of parallelogram frames. The members B and C are {C011- nected respectively to the diamond cutters D and D by mounting structures which will not be described in detail. The members B and C are extended oppositely outward with rollers E and F at their outer ends constituting followers. These are respectively in engagement with patterns or templates G and H for the contours to be trimmed. In the neutral position of the pantographs illustrated in Fig. 1 the members B, B C, C are all vertical and parallel to each other. I and J are the stationary pivots of the pantographs extending outward from the back plate A and so located that the diamond cutters D, D and their mounting structures are spaced from each other to provide clearance for 2,807,255 Patented Sept. 24, 1957 operation. This position is the closest approach to each other of the cutters and their mountings so that in no F in this position engage corresponding points in the pattern contours. As specifically illustrated the pattern contours include involute portions G, H which correspond to gear teeth on opposite sides of an interdental space. The patterns also include portions G H corresponding to the root portions of said teeth and extending at least half way across said interdental space. The followers in the position shown are in engagement with the portions G and H adjacent to ancuate curves G and H connecting said portions to the involute portions G, H. This corresponds to points in the contour to be trimmed which are at the roots of the respective teeth and separated from each other by the interdental space. If either follower is moved from this point along the portion G or H the cutter will be moved across the bottom of the interdental space to the common point in the contour reached by both cutters. Thus, to avoid interference when one follower is travelling over this portion of its pattern, the other follower will travel along the involute portion which will move their corresponding cutters further apart from each other than in the position shown.

To insure that the followers will move as just described the members B and C are connected by rods K and L to a common actuating member M. This is a horizontally extending bar to the opposite sides of which the rods K and L are pivotally connected at K, L to extend obliquely upward therefrom to the members B 0*. These rods K and L are also pivotally connected .to the latter at K L so that if the bar M is moved longitudinally in one direction, one of the followers will travel along the portion G or H While the other will travel downward along the involute portion G or H. Springs, N, N connected respectively to the members B C and extending obliquely downward to anchor points N N are under sufficient tension to hold the followers against their respective patterns. The pivot L is adjustable in position on the bar M by means of a block M engaging a slot M in said bar and clamped in different positions of adjustment by a headed screw M and clamping nut M For actuating the bar M it is connected at its opposite ends to the opposite end of a piston rod 0, the piston O of which is in a hydraulic cylinder P. The latter is supported by studs Q extending thereto outward from the back plate A. Shoulders Q on these studs contact with the back plate and nuts Q engaging threaded portions of the stud in rear of said plate clamp them rigidly in position. The bar M is further guided in its movement by a parallel rod R secured thereto by a bracket R and slidable in a bearing R on the back plate. The hydraulic connections to the cylinder P and their controlling valves are not shown but it will be understood that they are such that the piston 0 will be moved from one end of the cylinder to the other in reverse directions. Any lealcage of the fluid will in no way affect the operation for the bar M and rods K and L positively determine the relation of the followers E and F in all positions of movement thereof.

What I claim as my invention is:

1. A form trimmer comprising separate cutter actuating trimming mechanisms mounted for movement of the cutter of each to a common point in a contour to be trimmed, a pattern for guiding each mechanism to trace with the cutter thereof the corresponding portion of said contour including said common point, means for actuating both mechanisms to simultaneously follow their respective patterns and to trace'withtheircutters, in out of phase relationship, the corresponding portions of the contour to be trimmed including said common point, and interconnecting means between said mechanisms for holding their cutters in all positions of their movements positively spaced by a minimum distance sufiicient to prevent interference between said mechanisms.

2. The construction as in claim 1 in which said trimming mechanisms each includes a pantograph having a pattern follower, and a connection between said followers permitting the free movement of 631C111 to follow its pattern but positively limiting relative movement of said followers in directions resulting in movement of said cutters towards each other to maintain clearance between said mechanisms.

3. The construction as in claim 2 in which said patterns are spaced from each other and held in rigid relation, said actuating means including a horizontally reciprocating bar intermediate said patterns, and oppositely and obliquely extending rods between said bar and followers pivotally attached to each constituting the means for positively limiting relative movement of said followers in the directions aforesaid.

No references cited. 

